add check for attribute option values

Author: torhoehn

app/code/Magento/Catalog/Controller/Adminhtml/Product/Attribute/Validate.php

@@ -252,7 +252,7 @@ private function checkUniqueOption(DataObject $response, array $options = null)
     private function checkEmptyOption(DataObject $response, array $optionsForCheck = null)
     {
         foreach ($optionsForCheck as $optionValues) {
-            if (isset($optionValues[0]) && $optionValues[0] == '') {
+            if (isset($optionValues[0]) && trim($optionValues[0]) == '') {
                 $this->setMessageToResponse($response, [__("The value of Admin scope can't be empty.")]);
                 $response->setError(true);
             }

app/code/Magento/ConfigurableProduct/view/adminhtml/web/js/variations/steps/attributes_values.js

@@ -106,6 +106,7 @@ define([
                 errorOption,
                 allOptions = [];
 
+            newOption.label = $.trim(option.label);
             if (_.isEmpty(newOption.label)) {
                 return false;
             }